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Cerium salt, producing method thereof, cerium oxide and cerium based polishing slurry

a technology of cerium oxide and cerium salt, which is applied in the direction of lanthanide oxide/hydroxide, manufacturing tools, other chemical processes, etc., can solve the problem of difficult to reduce the scratch on the surface being polished, and achieve the effect of reducing the scratch and reducing the scratch

Inactive Publication Date: 2007-07-19
HITACHI CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The invention relates to a cerium-based polishing slurry that can be used with reduced scratches on surfaces that need to be precisely polished, such as semiconductors, liquid crystal displays, and hard discs. The invention aims to reduce scratches by reducing the amount of fine particles of impurities in the cerium oxide particles used in the polishing slurry. The invention provides a cerium salt with a reduced amount of insoluble components, a method for producing the cerium salt, and a cerium oxide obtained by subjecting the cerium salt to a high temperature process. The cerium-based polishing slurry and the cerium oxide according to the invention have a reduced concentration of insoluble components, resulting in a more effective polishing process with reduced scratches on surfaces.

Problems solved by technology

However, when cerium oxide that is produced by processing at high temperatures the cerium salt obtained according to those methods is used as polishing particles in a cerium oxide based polishing slurry, it is difficult to reduce the scratch on a surface being polished.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0064] In what follows, the invention will be specifically detailed with reference to examples. However, the invention is not limited to the examples.

[0065] (Purification of Cerium Carbonate)

[0066] Into 150 g of 6N nitric acid, 240 g of commercially available cerium carbonate hexahydrate was dissolved, and thereby 390 g of a cerium carbonate solution was obtained. The solution of 390 g was subjected to a centrifugal separation at the revolution number of 1000 rpm for 120 min. Immediately after a separator is stopped, 350 g of supernatant liquid was sampled.

[0067] In 250 g of pure water, 50 g of ammonium hydrogen carbonate was dissolved, followed by filtering with a 0.1 μm filter. The filtrate was added to 350 g of the above sampled supernatant liquid and a precipitate of cerium carbonate was obtained. When the precipitate was recovered, cleansed and dried, a recovery rate of cerium was substantially 100%.

[0068] The above operation was repeated, and thereby 6 kg in total of ceriu...

example 2

[0082] (Purification of Cerium Carbonate)

[0083] With filters respectively having pore diameters of 10.0 μm, 5.0 μm, 1.0 μm and 0.1 μm, 390 g of a cerium carbonate-dissolved solution prepared under the same conditions as that of example 1 was filtered stepwise with suction, and thereby a filtrate of 390 g was sampled.

[0084] To 390 g of the filtrate, a filtrate of ammonium hydrogen carbonate obtained by dissolving and filtering under the same conditions as that of example 1 was added, and thereby a precipitate of cerium carbonate was obtained. When the precipitate was recovered, cleansed and dried, a recovery rate of cerium was substantially 100%.

[0085] The above operation was repeated and 6 kg in total of cerium carbonate was prepared.

[0086] In nitric acid and aqueous hydrogen peroxide, 20 g of the purified cerium carbonate was dissolved under the same conditions as that of the case of cerium carbonate purified in example 1, followed by filtering with an analyzing filter, further...

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Abstract

A cerium salt wherein, when 20 g of the cerium salt is dissolved in a mixed liquid of 12.5 g of 6N nitric acid and 12.5 g of a 30% hydrogen peroxide aqueous solution, a concentration of an insoluble component present in the solution is 5 ppm or less by mass ratio to the cerium salt before dissolution and cerium oxide produced by processing the cerium salt at high temperatures. Scratch on a surface to be polished can be reduced when a cerium based polishing slurry containing the cerium oxide particles is used, since an amount of impurities in cerium oxide particles and cerium salt particles, raw material thereof, is reduced for high purification.

Description

TECHNICAL FIELD [0001] The present invention relates to a high purity cerium salt in which impurity particles are reduced and a producing method thereof, cerium oxide obtained by processing the cerium salt at a high temperature, and a cerium based polishing slurry that uses the cerium oxide. BACKGROUND ART [0002] As examples that necessitate accurately polishing a surface of a material, an optical disc substrate, a magnetic disc, a glass substrate for use in flat panel displays, a watch plate, a camera lens, a glass material used for various kinds of lenses for use in optical components, a crystal material such as filters, a substrate such as silicon wafer for use in semiconductor or the like, and an insulating film, a metal layer, a barrier layer and so on formed in the respective steps in the manufacture of a semiconductor device can be cited. Surfaces of the materials are required to polish with high precision. Accordingly, a polishing agent in which for instance silica, zirconiu...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C01F17/00C01F17/235C09G1/02C09K3/14H01L21/3105H01L21/321
CPCC01F17/0043C01F17/005C01P2004/61H01L21/31053C09G1/02C09K3/1409C09K3/1463C01P2004/62C01F17/247C01F17/235C01F17/10
Inventor CHINONE, KANSHIMIYAOKA, SEIJI
Owner HITACHI CHEM CO LTD
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